We applied fluorogenic methylumbelliferyl compounds to measure enzyme activities (ß‐glucosidase, cellobiohydrolase, and ß‐xylosidase) in a wetland peat. The enzyme activities showed substrate saturation around 400 μM and approximate linearity for at least 100 minutes incubation time. The effects of phenolics and toluene on the enzymes were small. All enzyme activities increased with increasing incubation temperature. Beta‐glucosidase and ß‐xylosidase showed optimal activities in an acidic condition (pH 5), while cellobiohydrolase had the highest activity in a neutral pH. The method would be effective in samples with low enzyme activities and interferences from organic compounds.